to rent or sell? opinions required

Hi,

Need some opinions on what move I should make.

Currently I own an apartment which I'm living in, its worth 525-550k.
My wife works for herself and needs to find a new location to practise, office rental is very over priced in our area ($1300pm+).
For the same price as the repayments on the apartment and a few hundred less the cost of a office, we can rent a house which the wife can work from (obviously we will live there too).

I also own (in partnership) a house (outer suburbs) with room to build 2 units in the rear, planning permits will be approved in the next month or so. 

So my decision is whether I should keep the apartment (which is positive by around $530pm) or sell the apartment (no CGT) and use the profit of around 220k to buy another (in partnership) house with backyard to development.

I’m lucky because my investment partner is highly experienced and has a good team setup.

I can hold and rent the apartment and have better cash flow then living there.
Or I can sell the apartment and reinvest in another development.

I plan to continue to do backyard developments (in partnership) build and sell until I’m in a position to hold units without having the borrow.

My salary is fairly low (66k ex super) so I’m doing the current development with a pretty tight budget.
I should get a salary increase of about 15k in around 12months, which will relax the budget nicely.
Because my wife's income isn't regular, we can only count on it to pay half the house rent (which would be her office rent) and a few hundred towards foods etc.

The apartment is located near a major uni and is very easily rented, so holding it is easy. However with my salary I can’t access the equity because I can’t afford further repayments. I can't see the price going up much (compared to the last 5years) in the next 5-7 years.

 Can you guys please give me some opinions?